An electrical connection box that connects a battery and various electric devices is mounted on a vehicle (see, JP2013-226019A). Electric components (relays, fuses, and the like) and circuit bases (circuit boards, bus bars, and the like) are mounted on the electrical connection box.
Grounding conductors are provided in a part of the circuit bases, and many of the ground conductors are connected to ground points outside the electrical connection box by a conductor wire such as an electric wire in a properly aggregated form. Alternatively, a ground circuit is incorporated in a connector in the electrical connection box so that a ground conductor is grounded through a ground circuit of a mating connector.
However, the related art electrical connection box has an integral structure with the electric component and circuit bases. Accordingly, the entire electrical connection box has to be designed and manufactured every time specifications of electric components or circuit bases change, resulting in a high cost of the electrical connection box.